FOR M 2
THE P(A3T9E NoTfS 1A9C7T0,) 1970 THE PATENTS& RULES, 2003 COMPLETE SPECIFICATION [See section 10, Rule 13] AC ELECTRIC ROLLING STOCK CONTROLLER;
MITSUBISHI ELECTRIC CORPORATION, A CORPORATION ORGANISED
AND EXISTING UNDER THE LAWS OF JAPAN, WHOSE ADDRESS IS 7-3,
MARUNOUCHI 2-CHOME, CHIYODA-KU, TOKYO 1008310, JAPAN
THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE
INVENTION AND THE MANNER IN WHICH IT IS TO BE PERFORMED.
2
DESCRIPTION
Field
[0001] The present invention relates to an alternating
5 current (AC) electric rolling stock controller that
receives AC power from an AC trolley for running.
Background
[0002] An AC electric rolling stock controller includes
10 a converter, a smoothing capacitor, and an inverter. AC
power supplied from an AC trolley is converted into direct
current (DC) power in the converter, and the DC power
obtained by the conversion is then charged in the smoothing
capacitor. The AC electric rolling stock controller
15 determines that charging of the smoothing capacitor is
complete when the charging voltage of the smoothing
capacitor reaches a start-up voltage. The start-up voltage
is a threshold voltage for determining completion of
initial charging. Upon completion of the initial charging,
20 the inverter starts to operate, thereby causing the motor
of the AC electric rolling stock to be driven. Starting of
rotation of a motor of an AC electric rolling stock is
hereinafter referred to as start-up.
[0003] Patent Literature 1 listed below discloses, as a
25 conventional technology, a technology that, during initial
charging of a smoothing capacitor, monitors the charging
voltage of the smoothing capacitor, and adjusts the
charging voltage of the smoothing capacitor in response to
variation in the trolley voltage, which is the voltage of
30 the AC trolley, even after the charging voltage of the
smoothing capacitor reaches the start-up voltage, thus to
perform the initial charging taking into consideration a
variation in the trolley voltage.
3
[0004] Patent Literature 1 describes that control of the
differential voltage between the trolley voltage and the
charging voltage of the smoothing capacitor at a constant
level enables an inrush current to be suppressed, and
5 overcharging to be prevented, even at a high trolley
voltage.
Citation List
Patent Literature
10 [0005] Patent Literature 1: Japanese Patent Application
Laid-open No. H08-168101
Summary
Technical Problem
15 [0006] In the technology of Patent Literature 1 listed
above, no consideration is given to waveform distortion of
the trolley voltage. This presents a problem in that
distortion of the waveform of the trolley voltage leads to
a longer charging time of the smoothing capacitor than when
20 the waveform is not distorted, thereby causing a delay of
completion time of the initial charging.
[0007] In addition, in the technology of Patent
Literature 1 listed above, an increase in the trolley
voltage will cause the charging voltage of the smoothing
25 capacitor to be adjusted to a higher voltage depending on
the increased value of the trolley voltage. This means
that the start-up voltage for determination of completion
of the initial charging is reset to a higher voltage during
the initial charging. In this case, concern will arise
30 that if the start-up voltage that has been reset is not
suitably set for the amount of the waveform distortion of
the trolley voltage, the charging voltage of the smoothing
capacitor will be impeded from reaching the start-up
4
voltage, and the initial charging will thus not be complete.
[0008] The present invention has been made in view of
the foregoing, and it is an object of the present invention
to provide an AC electric rolling stock controller capable
5 of quickly and reliably starting up the AC electric rolling
stock even when the waveform of the trolley voltage is
distorted.
Solution to Problem
10 [0009] To solve the problem and achieve the object
described above, the present invention is directed to an
alternating current (AC) electric rolling stock controller
disposed in an AC electric rolling stock. The AC rolling
stock includes a converter that converts an AC voltage
15 supplied from an AC trolley into a direct current (DC)
voltage, and a smoothing capacitor that smoothens the DC
voltage output from the converter to control initial
charging of the smoothing capacitor. The AC electric
rolling stock controller includes: a first comparator that
20 compares an intermediate link voltage, which is a voltage
generated at the smoothing capacitor, with a first
threshold; a second comparator that compares the
intermediate link voltage with a second threshold less than
the first threshold; and a delayer that delays an output of
25 the second comparator. It is determined that the initial
charging of the smoothing capacitor is complete in a case
in which at least one of an output of the first comparator
and an output of the delayer is significant.
30 Advantageous Effects of Invention
[0010] An AC electric rolling stock controller according
to the present invention provides an advantage in being
capable of quickly and reliably starting up an AC electric
5
rolling stock even when the waveform of the trolley voltage
is distorted.
Brief Description of Drawings
5 [0011] FIG. 1 is a configuration diagram of a drive
system of an AC electric rolling stock including an AC
electric rolling stock controller according to a first
embodiment.
FIG. 2 is a block diagram illustrating a configuration
10 of the computer in the first embodiment.
FIG. 3 is a diagram illustrating an example for a
method of determining a setting value A in the first
embodiment.
FIG. 4 is a diagram illustrating behaviors of each
15 voltage in the drive system of FIG. 1. FIG. 5 is a first
diagram for describing an inrush current in the AC electric
rolling stock controller of the first embodiment.
FIG. 6 is a second diagram for describing an inrush
current in the AC electric rolling stock controller of the
20 first embodiment.
FIG. 7 is a first diagram for describing the reason
for including the comparator 24 in the computer of the
first embodiment.
FIG. 8 is a second diagram for describing the reason
25 for including the comparator 24 in the computer of the
first embodiment.
FIG. 9 is a block diagram illustrating a configuration
of a computer in a second embodiment.
FIG. 10 is a diagram for describing operation of the
30 computer in the second embodiment.
FIG. 11 is a block diagram illustrating a
configuration of a computer in a third embodiment.
FIG. 12 is a block diagram illustrating an example of
6
hardware configuration of each of the computers of the
first through third embodiments.
FIG. 13 is a block diagram illustrating another
example of hardware configuration of each of the computers
5 of the first through third embodiments.
Description of Embodiments
[0012] An AC electric rolling stock controller according
to embodiments of the present invention will be described
10 in detail below with reference to the drawings. Note that
the following embodiments are not intended to limit the
scope of the present invention. In addition, in the
following embodiments, electrical connection and physical
connection are not distinguished from each other, and are
15 referred to simply as “connection”.
[0013] First Embodiment.
FIG. 1 is a configuration diagram of a drive system
100 of an AC electric rolling stock including an AC
electric rolling stock controller 50 according to a first
20 embodiment. As illustrated in FIG. 1, the drive system 100
of an AC electric rolling stock, according to the first
embodiment, includes a pantograph 1, a circuit breaker 2, a
main transformer 3, the controller 50, motors 16, and an AC
voltage detector 14. The AC voltage detector 14 is
25 hereinafter referred to as “ACPT 14”.
[0014] In FIG. 1, the pantograph 1 receives AC power
from an AC trolley 101. The main transformer 3 has a
primary winding 3a that receives the AC power supplied
through the pantograph 1. An AC voltage generated at a
30 secondary winding 3b of the main transformer 3 is applied
to the AC electric rolling stock controller 50. A circuit
breaker 2 is disposed between the pantograph 1 and the main
transformer 3. The circuit breaker 2 is a device disposed
7
on the power cable connecting together the pantograph 1 and
the main transformer 3, and is capable of interrupting
current flowing between the pantograph 1 and the main
transformer 3. An example of the circuit breaker 2 is a
5 vacuum circuit breaker (VCB). The motors 16 are targets to
be controlled by the controller 50, and are each an AC
motor that drives an axle (not illustrated) of the AC
electric rolling stock. The ACPT 14 detects an
instantaneous value of the trolley voltage output by the AC
10 trolley 101. In FIG. 1, the value detected by the ACPT 14
is denoted by “VAC1”. The detected value of the
instantaneous value of the trolley voltage is hereinafter
referred to as “trolley voltage instantaneous value VAC1”.
The trolley voltage instantaneous value VAC1 detected by the
15 ACPT 14 is input to a controller 12 which will be described
later.
[0015] A configuration and functionality of the
controller 50 will next be described. The controller 50
includes, as illustrated in FIG. 1, a charging resistor 4,
20 a charging contactor 5, a main contactor 6, a converter 8,
a smoothing capacitor 9, a DC voltage detector 10, an
inverter 11, and the controller 12. The controller 12
includes a computer 20. The DC voltage detector 10 is
hereinafter referred to as “DCPT 10”.
25 [0016] The charging contactor 5 and the main contactor 6
are connected in parallel with each other between the main
transformer 3 and the converter 8, and are inserted in the
charging path of the smoothing capacitor 9. Openingclosing
control of each of the charging contactor 5 and the
30 main contactor 6 is provided by the controller 12. The
charging contactor 5 is a contactor closed during initial
charging of the smoothing capacitor 9, and opened after
completion of the initial charging. The main contactor 6
8
is a contactor opened during the initial charging of the
smoothing capacitor 9, and closed after completion of the
initial charging. The charging resistor 4 is connected in
series with the charging contactor 5.
5 [0017] The converter 8 is a PWM converter. The AC
voltage generated at the secondary winding 3b of the main
transformer 3 is applied to the converter 8. The converter
8 converts the applied AC voltage into a DC voltage. The
smoothing capacitor 9 smoothens the DC voltage output by
10 the converter 8. The smoothed DC voltage is maintained on
the smoothing capacitor 9. The inverter 11 converts the DC
voltage maintained on the smoothing capacitor 9 into an AC
voltage. The AC voltage obtained by conversion is applied
to the motors 16 to drive the motors 16.
15 [0018] The DCPT 10 detects the voltage across the
smoothing capacitor 9. In FIG. 1, the value detected by
the DCPT 10 is denoted by “VEFC”. Note that, considering
the position of the smoothing capacitor 9 between the
converter 8 and the inverter 11, the voltage generated at
20 the smoothing capacitor 9 may sometimes be referred to as
intermediate link voltage. Thus, the detected value of the
voltage across the smoothing capacitor 9 is hereinafter
referred to as “intermediate link voltage VEFC”. The
intermediate link voltage VEFC detected by the DCPT 10 is
25 input to the controller 12.
[0019] An operation of the drive system 100 of an AC
electric rolling stock to charge the smoothing capacitor 9
will next be described with reference to FIG. 1.
[0020] The AC voltage received from the AC trolley 101
30 is applied to the primary winding 3a of the main
transformer 3 through the pantograph 1. The AC voltage
applied to the primary winding 3a of the main transformer 3
is stepped down by the main transformer 3, and the AC
9
voltage stepped down is output from the secondary winding
3b. Upon start-up of the AC electric rolling stock, the
charging contactor 5 is closed first. In this situation,
the main contactor 6 is in an open state. This causes the
5 smoothing capacitor 9 to be charged through the charging
resistor 4 and through the charging contactor 5.
[0021] During the initial charging of the smoothing
capacitor 9, a switching device (not illustrated) provided
in the converter 8 has not performed switching operation.
10 Thus, a charging current to charge the smoothing capacitor
9 flows through a diode (not illustrated) provided in the
converter 8. That is, during the initial charging of the
smoothing capacitor 9, the converter 8 operates as a diode
converter that provides rectification.
15 [0022] Upon completion of the initial charging, the main
contactor 6 is closed, and the charging contactor 5 is
opened. The charging contactor 5 is opened after closing
of the main contactor 6. The inverter 11 starts to operate,
and the AC electric rolling stock is started. The
20 controller 12 monitors the intermediate link voltage VEFC,
and controls the converter 8 such that an amount of power
to drive the motors 16 is constantly maintained in the
smoothing capacitor 9. In this situation, the switching
device (not illustrated) provided in the converter 8 is
25 controlled using pulse width modulation (PWM) control by
the controller 12. That is, in charging control of the
smoothing capacitor 9 after the initial charging, the
converter 8 operates as a switching converter.
[0023] The computer 20 provided in the controller 12
30 will next be described with reference to FIGS. 2 and 3.
FIG. 2 is a block diagram illustrating a configuration of
the computer 20 in the first embodiment. FIG. 3 is a
diagram illustrating an example for a method of determining
10
a setting value A in the first embodiment.
[0024] The computer 20 includes a trolley voltage root
mean square (RMS) value calculator 21, comparators 23 and
24, a delayer 26, and an OR circuit 27.
5 [0025] The trolley voltage RMS (root mean squared)value
calculator 21 receives the trolley voltage instantaneous
value VAC1 detected by the ACPT 14. The trolley voltage RMS
value calculator 21 calculates a trolley voltage RMS value
VS using the trolley voltage instantaneous value VAC1. The
10 trolley voltage RMS value VS is an RMS value of the trolley
voltage output from the AC trolley 101.
[0026] The comparator 23 receives the trolley voltage
RMS value VS calculated by the trolley voltage RMS value
calculator 21, the intermediate link voltage VEFC detected
15 by the DCPT 10, and a start-up command SC. The start-up
command SC is a signal to command starting up of the AC
electric rolling stock. The start-up command SC is output
from a cab (not illustrated), an operation management
device (not illustrated) disposed on the AC electric
20 rolling stock, or the like.
[0027] The comparator 23 compares the intermediate link
voltage VEFC with a determination threshold, i.e., a setting
value A. That is, the comparator 23 makes a comparison on
magnitude relationship between the intermediate link
25 voltage VEFC and the setting value A. In a case in which
the intermediate link voltage VEFC is greater than the
setting value A, the comparator 23 determines that the
comparison result of the comparator 23 is significant, and
outputs a logical “1” to the OR circuit 27. Otherwise, in
30 a case in which the intermediate link voltage VEFC is less
than or equal to the setting value A, the comparator 23
determines that the comparison result of the comparator 23
is not significant, and outputs a logical “0” to the OR
11
circuit 27.
[0028] Although the foregoing description describes that
a logical “1” is output to the OR circuit 27 in a case in
which the intermediate link voltage VEFC is greater than the
5 setting value A, a logical “1” may also be output to the OR
circuit 27 in a case in a which the intermediate link
voltage VEFC is equal to the setting value A. That is, a
logical “1” may be output to the OR circuit 27 in a case in
which the intermediate link voltage VEFC is greater than or
10 equal to the setting value A.
[0029] The setting value A is calculated from the
trolley voltage RMS value VS. FIG. 3 illustrates an
example of a method of determining the setting value A for
an AC trolley having a nominal voltage of 25 kV. The
15 horizontal axis of FIG. 3 represents the trolley voltage
RMS value VS, and the vertical axis of FIG. 3 represents
the setting value A. The voltage on the AC trolley having
a nominal voltage of 25 [kV] varies up to plus or minus
approximately a dozen percent depending on the load
20 condition. Accordingly, the example of FIG. 3 assumes that
the amount of increase is proportional to the trolley
voltage RMS value VS when the trolley voltage RMS value VS
is greater than VS1 [kV] and less than VS2 [kV]. In
addition, when the trolley voltage RMS value VS is less
25 than or equal to VS1 [kV], the setting value A is
determined to be A1; and when the trolley voltage RMS value
VS is greater than or equal to VS2 [kV], the setting value A
is determined to be A2. Note that A1 and A2 satisfy a
relationship of A1B. The setting
value B may be a fixed value, or may be a value varied
depending on the setting value A. The advantage of use of
the setting value B will be described later.
[0034] As described above, the OR circuit 27 receives
10 the output of the comparator 23 and the output of the
delayer 26. In a case in which at least one of the output
of the comparator 23 and the output of the delayer 26 is a
logical “1”, the OR circuit 27 outputs a signal TC, which
indicates completion of the initial charging of the
15 smoothing capacitor 9. The signal TC is hereinafter
referred to as “initial charging completion signal TC”.
When the OR circuit 27 outputs the initial charging
completion signal TC, the controller 12 provides the
opening-closing control described above on the charging
20 contactor 5 and on the main contactor 6.
[0035] FIG. 4 is a diagram illustrating behaviors of
each voltage in the drive system 100 of FIG. 1. The top
portion, the middle portion, and the bottom portion of FIG.
4 respectively illustrate time-varying waveforms of a
25 secondary voltage, of a rectified voltage, and of the
intermediate link voltage VEFC in a case in which the startup
command is input at time t0.
[0036] The secondary voltage illustrated in the top
portion of FIG. 4 represents the waveform of the AC voltage
30 generated at the secondary winding 3b of the main
transformer 3. The rectified voltage illustrated in the
middle portion of FIG. 4 represents the waveform of the
rectified voltage, which is the output voltage of the
14
converter 8 when the converter 8 operates as a diode
converter. The term of rectified voltage means that the
smoothing capacitor 9 is not connected to the output side
of the converter 8. In contrast, the intermediate link
5 voltage VEFC illustrated in the bottom portion of FIG. 4
represents the waveform when the smoothing capacitor 9 is
connected to the output side of the converter 8. When the
smoothing capacitor 9 is connected to the output side of
the converter 8, the output voltage of the converter 8 has
10 a smoothed waveform such as one illustrated in the bottom
portion of FIG. 4.
[0037] In the waveform in each of the top portion, the
middle portion, and the bottom portion of FIG. 4, the bold
solid line represents the waveform for an undistorted
15 trolley voltage, while the bold broken line represents the
waveform for a distorted trolley voltage. Moreover, the
bottom portion of FIG. 4 illustrates, using the broken line,
the waveform of the solid line in the middle portion of FIG.
4, i.e., the waveform of the rectified voltage for an
20 undistorted trolley voltage.
[0038] When the waveform of the trolley voltage is
distorted to drop around the peak value of the trolley
voltage as illustrated by the broken line in the top
portion of FIG. 4, the intermediate link voltage VEFC is
25 reduced, as illustrated by the broken line in the bottom
portion of FIG. 4, as compared to when the waveform of the
trolley voltage is not distorted.
[0039] FIG. 5 is a first diagram for describing an
inrush current in the AC electric rolling stock controller
30 50 of the first embodiment. FIG. 6 is a second diagram for
describing an inrush current in the AC electric rolling
stock controller 50 of the first embodiment.
[0040] As described above, when the waveform of the
15
trolley voltage is distorted to drop around the peak value,
the intermediate link voltage VEFC is reduced as compared to
when the trolley voltage is not distorted. An equivalent
circuit of the charging circuit during charging of the
5 smoothing capacitor 9 can be illustrated in a simplified
manner as FIG. 5, where “V2” denotes the intermediate link
voltage VEFC, i.e., the charging voltage of the smoothing
capacitor 9, in this situation, and “V1” denotes the RMS
value of the rectified voltage output from the converter 8.
10 In FIG. 5, the voltage V1 of a DC power supply 40
corresponds to the RMS value of the rectified voltage, and
the charging voltage V2 of the smoothing capacitor 7
corresponds to the intermediate link voltage VEFC. Then,
the circuit is formed by the DC power supply 40 and the
15 smoothing capacitor 9 connected to each other via an
equivalent resistance 42 in the charging circuit. A
greater differential voltage between the voltage V1 and the
charging voltage V2 results in a more rapid change in the
voltage immediately after the voltage V1 is applied as
20 illustrated in FIG. 6. In addition, the equivalent
resistance 42 in the charging circuit is very low, thereby
causing a high inrush current to flow through the smoothing
capacitor 9.
[0041] FIG. 7 is a first diagram for describing the
25 reason for including the comparator 24 in the computer 20
of the first embodiment. FIG. 8 is a second diagram for
describing the reason for including the comparator 24 in
the computer 20 of the first embodiment.
[0042] In a case in which the waveform of the trolley
30 voltage is distorted, the value of the intermediate link
voltage VEFC may never reach the setting value A depending
on the setting value A as illustrated in FIG. 7. On the
other hand, in view of the problem of an inrush current
16
described above, the setting value A needs to be set to
avoid a great differential voltage between V1 and V2,
thereby hindering use of an extremely low value for the
setting value. Thus, in the first embodiment, the concept
5 of the setting value A of suppressing an inrush current is
left unchanged, and instead, the comparator 24, which uses
the setting value B having a concept different from the
concept of the setting value A, is included.
[0043] FIG. 8 illustrates the waveform of the
10 intermediate link voltage VEFC that is the same as that
illustrated in FIG. 7. The setting value A is also at the
same value. In addition, FIG. 8 illustrates a situation in
which the intermediate link voltage VEFC reaches the setting
value B at time t1, and charging is complete at time t2.
15 The difference between time t2 and time t1 is a delay time
that is set by the delayer 26.
[0044] To address the problem of distortion of the
waveform of the trolley voltage described above, the
setting value B is set to a value that ensures a reliable
20 determination on completion of charging even when the
waveform of the trolley voltage is distorted. As described
above, the setting value A and the setting value B satisfy
a relationship of A>B. Meanwhile, simply using the setting
value B satisfying such relationship may cause the problem
25 of an inrush current described above. However, the
configuration of the first embodiment causes the
determination on completion of charging to be suspended for
a delay time by the action of the delayer 26 even when the
intermediate link voltage VEFC has reached the setting value
30 B. As illustrated in FIGS. 7 and 8, the waveform of the
intermediate link voltage VEFC becomes a waveform that rises
with the time constant of the charging circuit. Thus,
making a determination of the setting value B in
17
consideration of distortion of the waveform of the trolley
voltage first, and then a determination of the delay time
of the delayer 26 for the setting value B determined, based
on an accepted value of inrush current enables the
5 intermediate link voltage VEFC to reliably reach the startup
voltage while suppressing an inrush current.
[0045] As described above, the AC electric rolling stock
controller according to the first embodiment determines
that initial charging of the capacitor is complete when the
10 result of the comparison between the intermediate link
voltage and the setting value A is significant, or when the
delayed output of the result of the comparison between the
intermediate link voltage and the setting value B is
significant. This enables the intermediate link voltage
15 VEFC to reliably reach the start-up voltage while
suppressing an inrush current into the smoothing capacitor.
This enables the AC electric rolling stock to quickly and
reliably start up even when the waveform of the trolley
voltage is distorted.
20 [0046] Second Embodiment.
FIG. 9 is a block diagram illustrating a configuration
of a computer 20A in a second embodiment. In the computer
20A illustrated in FIG. 9, the comparator 23 in the
configuration of the computer 20 of the first embodiment
25 illustrated in FIG. 2 has been replaced with a comparator
25. In addition, the computer 20A further includes a
trolley voltage peak value calculator 28 and an addersubtractor
29, which are added to the configuration of the
computer 20 of the first embodiment illustrated in FIG. 2.
30 The computer 20A is configured such that an output of the
adder-subtractor 29 is input to the comparator 25. The
other part of the configuration is identical or similar to
the configuration of the first embodiment. Identical or
18
similar configuration elements are designated by the same
reference characters, and duplicate description will be
omitted.
[0047] The trolley voltage peak value calculator 28
5 receives the trolley voltage instantaneous value VAC1. The
trolley voltage peak value calculator 28 calculates a
trolley voltage peak value VP, which is the peak value of
the trolley voltage instantaneous value VAC1, using the
trolley voltage instantaneous value VAC1. Note that the
10 trolley voltage peak value calculator 28 may hold and
output the peak value of the trolley voltage instantaneous
value rather than directly calculating the trolley voltage
peak value VP.
[0048] The adder-subtractor 29 receives the trolley
15 voltage peak value VP calculated by the trolley voltage
peak value calculator 28 and the intermediate link voltage
VEFC detected by the DCPT 10. The adder-subtractor 29
generates a potential difference ΔV, which is the
differential voltage between the trolley voltage peak value
20 VP and the intermediate link voltage VEFC.
[0049] The comparator 25 receives the potential
difference ΔV generated by the adder-subtractor 29 and the
start-up command SC. The comparator 25 compares the
potential difference ΔV with a determination threshold,
25 i.e., a setting value C. That is, the comparator 25 makes
a comparison on magnitude relationship between the
potential difference ΔV and the setting value C. The
setting value C is, unlike the setting value A, a constant
setting value independent of the trolley voltage. In a
30 case in which the potential difference ΔV is less than the
setting value C, the comparator 25 determines that the
comparison result of the comparison unit 25 is significant,
and outputs a logical “1” to the OR circuit 27. Otherwise,
19
in a case in which the potential difference ΔV is greater
than or equal to the setting value C, the comparator 25
determines that the comparison result of the comparator 25
is not significant, and outputs a logical “0” to the OR
5 circuit 27.
[0050] Note that although the foregoing description
describes that a logical “1” is output to the OR circuit 27
in a case in which the potential difference ΔV is less than
the setting value C, a logical “1” may also be output to
10 the OR circuit 27 in a case in which potential difference
ΔV is equal to the setting value C. That is, a logical “1”
may be output to the OR circuit 27 in a case in which the
potential difference ΔV is less than or equal to the
setting value C.
15 [0051] The OR circuit 27 receives the output of the
comparator 25 and the output of the delayer 26. The
functionality and the actions of the comparator 24 and of
the delayer 26 are identical or similar to those of the
first embodiment. In a case in which at least one of the
20 output of the comparator 25 and the output of the delayer
26 is a logical “1”, the OR circuit 27 outputs an initial
charging completion signal TC indicating that the initial
charging of the smoothing capacitor 9 is complete. The
subsequent operation is identical or similar to the
25 operation of the first embodiment.
[0052] FIG. 10 is a diagram for describing operation of
the computer 20A in the second embodiment. FIG. 10
illustrates the waveform of the potential difference ΔV
output from the adder-subtractor 29. In addition, FIG. 10
30 illustrates a situation in which the potential difference
ΔV reaches the setting value C at time t3.
[0053] As described above, when the waveform of the
trolley voltage is distorted, the intermediate link voltage
20
VEFC is reduced as compared to when the waveform of the
trolley voltage is not distorted. This also applies to the
trolley voltage peak value VP. Therefore, when the
waveform of the trolley voltage is distorted, the trolley
5 voltage peak value VP is also reduced as compared to when
the waveform of the trolley voltage is not distorted. Thus,
there is likely to be a correlation between a variation in
the intermediate link voltage VEFC and a variation in the
trolley voltage peak value VP. Accordingly, in the second
10 embodiment, comparison of the potential difference ΔV
between the trolley voltage peak value VP and the
intermediate link voltage VEFC with the setting value C,
which is a determination threshold, enables the
intermediate link voltage VEFC to reliably reach the start15
up voltage even when the waveform of the trolley voltage is
distorted. This enables the AC electric rolling stock to
quickly and reliably start up even when the waveform of the
trolley voltage is distorted.
[0054] Note that the determination logic of the second
20 embodiment to compare the potential difference ΔV between
the trolley voltage peak value VP and the intermediate link
voltage VEFC with the setting value C is more reliable then
the determination logic of the first embodiment to make a
comparison on magnitude relationship between the
25 intermediate link voltage VEFC and the setting value A. As
such, the comparator 24, the delayer 26, and the OR circuit
27 that are auxiliarily provided may be removed from the
configuration of FIG. 9. In such configuration, initial
charging of the smoothing capacitor 7 can be determined to
30 be complete when the comparison result of the comparator 25
is significant.
[0055] Third Embodiment.
FIG. 11 is a block diagram illustrating a
21
configuration of a computer 20B in a third embodiment. In
the computer 20B illustrated in FIG. 11, the OR circuit 27
in the configuration of the computer 20A of the second
embodiment illustrated in FIG. 9 has been replaced with an
5 OR circuit 27B, and the comparator 23 in the computer 20 of
the first embodiment illustrated in FIG. 2 has been added.
That is, the computer 20B in the third embodiment is formed
by combination of the computer 20 in the first embodiment
illustrated in FIG. 2 and the computer 20A in the second
10 embodiment illustrated in FIG. 9. Note that configuration
elements identical or similar to the elements in the
configurations of the first embodiment and of the second
embodiment are designated by the same reference characters,
and duplicate description will be omitted.
15 [0056] The OR circuit 27B receives the output of the
comparator 23, the output of the comparator 25, and the
output of the delayer 26. In a case in which at least one
of the output of the comparator 23, the output of the
comparator 25, and the output of the delayer 26 is a
20 logical “1”, the OR circuit 27B outputs an initial charging
completion signal TC, which indicates completion of the
initial charging of the smoothing capacitor 9. The
subsequent operation is identical or similar to the
operation of the first and second embodiments.
25 [0057] According to the third embodiment: the feature of
the determination logic of the first embodiment to make a
comparison on magnitude relationship between the
intermediate link voltage VEFC and the setting value A; and
the feature of the determination logic of the second
30 embodiment to make a comparison on magnitude relationship
between the potential difference ΔV between the trolley
voltage peak value VP and the intermediate link voltage VEFC
and the setting value C; are utilized complementarily to
22
each other, and this enables a determination logic to be
established that is insusceptible to distortion of the
waveform of the trolley voltage. For example, the setting
value A is chosen to cause the comparator 23 to output a
5 logical “1” before the comparator 25 when the waveform of
the trolley voltage is not significantly distorted. In
addition, the setting value C is chosen to cause the
comparator 25 to output a logical “1” before the comparator
23 when the waveform of the trolley voltage is distorted,
10 for example, as illustrated in FIG. 4. Use of such setting
value A and setting value C enables a determination logic
to be established that is not significantly affected by
distortion of the waveform of the trolley voltage.
[0058] A hardware configuration for implementing each of
15 the computers in the first through third embodiments will
be described with reference to the drawings of FIGS. 12 and
13. FIG. 12 is a block diagram illustrating an example of
hardware configuration of each of the computers of the
first through third embodiments. FIG. 13 is a block
20 diagram illustrating another example of hardware
configuration of each of the computers of the first through
third embodiments.
[0059] To implement the functionality of each of the
computers in the first through third embodiments, a
25 configuration may be used, as illustrated in FIG. 12, that
includes a processor 200 that performs computation, a
memory 202 that stores a program to be read by the
processor 200, and an interface 204 that inputs and outputs
signals.
30 [0060] The processor 200 may be computing means such as
a computer, a microprocessor, a microcomputer, a central
processing unit (CPU), or a digital signal processor (DSP).
In addition, examples of the memory 202 include a non23
volatile or volatile semiconductor memory such as a random
access memory (RAM), a read-only memory (ROM), a flash
memory, an erasable programmable ROM (EPROM), or an
electrically EPROM (EEPROM) (registered trademark); a
5 magnetic disk, a flexible disk, an optical disk, a compact
disc, a MiniDisc, a digital versatile disc (DVD), and a
Blu-ray (registered trademark) disk (BD).
[0061] The memory 202 stores a program for performing
the functionality of each one of the computers and a table
10 referred to by the processor 200. The processor 200
provides and receives necessary information via the
interface 204. The processor 200 executes a program stored
in the memory 202, and the processor 200 refers to the
table stored in the memory 202. The computing processing
15 described above can thus be performed. The result of
computation by the processor 200 may be stored in the
memory 202.
[0062] In addition, the processor 200 and the memory 202
illustrated in FIG. 12 may be replaced with a processing
20 circuitry 203 as illustrated in FIG. 13. The processing
circuitry 203 is a single circuit, a set of multiple
circuits, an application specific integrated circuit (ASIC),
a field-programmable gate array (FPGA), or a combination
thereof.
25 [0063] Note that the configurations described in the
foregoing embodiments are merely examples of various
aspects of the present invention. These configurations may
be combined with a known other technology, and moreover, a
part of such configurations may be omitted and/or modified
30 without departing from the spirit of the present invention.
Reference Signs List
[0064] 1 pantograph; 2 circuit breaker; 3 main
24
transformer; 3a primary winding; 3b secondary winding; 4
charging resistor; 5 charging contactor; 6 main
contactor; 8 converter; 9 smoothing capacitor; 10 DC
voltage detector; 11 inverter; 12 controller; 14 AC
5 voltage detector; 16 motor; 20, 20A, 20B computer; 21
trolley voltage RMS value calculator; 23, 24, 25
comparator; 26 delayer; 27, 27B OR circuit; 28 trolley
voltage peak value calculator; 29 adder-subtractor; 40 DC
power supply; 42 equivalent resistance; 50 controller;
10 100 drive system; 101 AC trolley; 200 processor; 202
memory; 203 processing circuitry; 204 interface.
25
We Claim:
1. An alternating current (AC) electric rolling stock
controller disposed in an AC electric rolling stock
5 including a converter to convert an AC voltage from an AC
trolley into a direct current (DC) voltage, and a smoothing
capacitor to smooth the DC voltage output by the converter
to control initial charging of the smoothing capacitor, the
AC electric rolling stock controller comprising:
10 a first comparator to compare an intermediate link
voltage being a voltage generated at the smoothing
capacitor, with a first threshold;
a second comparator to compare the intermediate link
voltage with a second threshold less than the first
15 threshold; and
a delayer to delay an output of the second comparator,
wherein
it is determined that the initial charging of the
smoothing capacitor is complete in a case in which at least
20 one of an output of the first comparator and an output of
the delayer is significant.
2. The AC electric rolling stock controller according to
claim 1, comprising:
25 a root mean square value calculator to calculate a
root mean square value of a trolley voltage output from the
AC trolley, wherein
the first threshold and the second threshold are set
based on the root mean square value calculated of the
30 trolley voltage.
3. An alternating current (AC) electric rolling stock
controller disposed in an AC electric rolling stock
26
including a converter to convert, into a direct current
(DC) voltage, an AC voltage output from an AC trolley and
applied via a main transformer, and a smoothing capacitor
to smooth the DC voltage output by the converter to control
5 initial charging of the smoothing capacitor, the AC
electric rolling stock controller comprising:
a peak value calculator to calculate a peak value of a
trolley voltage output from the AC trolley; and
a first comparator to compare a differential voltage
10 between the peak value calculated of the trolley voltage
and an intermediate link voltage being a voltage generated
at the smoothing capacitor, with a first threshold, wherein
it is determined that the initial charging of the
smoothing capacitor is complete in a case in which an
15 output of the first comparator is significant.
4. The AC electric rolling stock controller according to
claim 3, wherein the first threshold is a constant setting
value independent of the trolley voltage.
20
5. The AC electric rolling stock controller according to
claim 3 or 4, comprising:
a second comparator to compare the intermediate link
voltage with a second threshold; and
25 a delayer to delay output of the second comparator,
wherein
it is determined that the initial charging of the
smoothing capacitor is complete in a case in which at least
one of an output of the first comparator and an output of
30 the delayer is significant.
6. An alternating current (AC) electric rolling stock
controller disposed in an AC electric rolling stock
27
including a converter to convert, into a direct current
(DC) voltage, an AC voltage output from an AC trolley and
applied via a main transformer, and a smoothing capacitor
to smooth the DC voltage output by the converter to control
5 initial charging of the smoothing capacitor, the AC
electric rolling stock controller comprising:
a first comparator to compare an intermediate link
voltage being a voltage generated at the smoothing
capacitor, with a first threshold;
10 a second comparator to compare the intermediate link
voltage with a second threshold less than the first
threshold;
a delayer to delay an output of the second comparator;
a peak value calculator to calculate a peak value of a
15 trolley voltage output from the AC trolley; and
a third comparator to compare a differential voltage
between the peak value calculated of the trolley voltage
and the intermediate link voltage being the voltage
generated at the smoothing capacitor, with a third
20 threshold, wherein
it is determined that the initial charging of the
smoothing capacitor is complete in a case in which at least
one of an output of the first comparator, an output of the
delayer, and an output of the third comparator is
25 significant.